The present invention relates generally to sharpener apparatus, and more particularly to a novel sharpener apparatus which enables a precise, repeatable beveled tip geometry to be formed on a workpiece, such as an electrode, without need for a highly skilled operator.
It is often necessary in the use of specialized equipment such as test apparatus which utilizes paired electrodes for creating electric discharge arcing, to provide a precise tip configuration or geometry on each electrode to insure accurate repeatability between tests. For example, in apparatus for performing comparative tracking index tests on dielectric insulating materials so as to measure the susceptibility of insulators to electrical short circuiting across the surface of the insulator in the presence of a liquid contaminant, generally termed tracking, a pair of electrodes are utilized to create a voltage discharge arcing adjacent the surface of the test specimen. See, for example, the standardized test described in the International Electrotechnical Commission Publication 112 (IEC 112) which is incorporated herein by reference. Under the IEC 112 test, a pair of standardized electrodes are positioned on a surface of a test sample of a dielectric insulator material and an electrolyte is deposited on the dielectric material between the electrodes by a dripping process. To improve repeatability of the test described in IEC 112, the tips of the electrodes are formed with a precise planar surface inclined to the longitudinal axis of the electrode. The electrode tip geometry is preferably reformed or cleaned by sharpening before each test as necessitated by erosion from electrical arcing. Thus, a need exists for an economical sharpener apparatus which enables highly accurate and repeatable tip geometries to be formed on electrodes without requiring a highly skilled operator.